Suppression of specific protein systhesis by antisense RNA is now established as a feasible technique. Our overall goal in this research is to suppress the expression of major histocompatibility antigens so as to improve the success of islet cell transplantation in the treatment of diabetes. This proposal will establish in cultured cells and animal models the possibility of using antisense RNA for this purpose. We have constructed a eukaryotic expression vector containing antisense Beta2-microglobulin (B2) and have stably transformed mouse cells and rat insulinoma cells. Preliminary results show suppression of surface B2 expression in some transformed cell lines. Cells deficient in B2 systhesis are known to show an accompanying lack of class I MHC expression. Our hypothesis is that suppression of B2 by antisense RNA will lead to suppression of MHC antigen expression. We propose to test the immune response to B2-minus cells by the mixed lymphocyte reaction and cytotoxic T lymphocyte assay. Tumor outgrowth studies will be performed with B2-deficient RIN cells in allogeneic rats. We propose to generate mice transgenic for antisense B2 cDNA by microinjection of one-cell embryos. Suppression of B2 synthesis and MHC expression by the transgene should allow tissue transplantation between transgenic mice and allogeneic strains. In the long term it may be possible to target expression of antisense B2 RNA to the pancreas of transgenic animals, providing a source of islet cells for transplantation. This research will provide insight into transplantation in diabetes with important scientific and potential therapeutic implications.